Piston for internal-combustion engines



1953 D. VON LASSBERG 2,657,961

PISTON FOR INTERNAL-COMBUSTION ENGINES Filed March 15, 1950 INVENTOR BYDIETRICH VON LASSBERG ATTORNEYS bustion chamber.

Patented Nov. 3, 1953 PISTON FOR INTERNAL-COMBUSTION ENGINES Dietrichvon Lassberg, Augsburg, Germany, as-

signor to Maschinenfabrik Augsburg Nm-nberg A. G., Augsburg, Germany, acorporation of Germany Application March. 15, 1950,.SerialNo.149,111

7 Claims. 1.

This invention relates to a piston for internal combustion engines.

It is the object of the present invention to provide. a. piston which isheat-resistant in case of very high, thermal stresseswithout requiring.artificial cooling and in which the. piston. body part bearing thepiston rings is kept so. cool that sticking of the piston. rings is.safely prevented.

With this and further objects in view which will hereinafter appear,according to the present invention the piston is made entirely or partlyof sintered metallic and ceramic powders, the ceramic powder havingspecial heat insulating and heat resistant properties and a high thermalshock resistance. The whole piston or only the upper part thereof mayconsist of a homogeneous powder composition. According to a specialfeature of the invention, however, the mixing ratio is graduallychanged, in such a way that the top of the piston consists of pureceramic powder while the percentage of metal powder is graduallyincreased and the material consists of pure metal powder at a certaindistance from the com- Thus it is possible to weld or sinter the upperpiston part consisting of this sintered mixture to a lower piston partconsisting of metal without ceramic admixtures while avoiding thedetrimental action of different coefiicients of thermal expansion at thejoint.

A piston according to the present invention ensures an efiicient heatinsulation without the requirement of a direct cooling.

Other and further objects, features and advantages of the invention willbe pointed out hereinafter and appear in the appended claims formingpart of the application,

In the accompanying drawing a now preferred embodiment of the inventionis shown by way of illustration and not by way of limitation.

The drawing shows an axial section of a piston having the inventionapplied thereto. It will be seen that the top part of the piston Iconsists of a sintered mixture of a heat-insulating, heat-resistantpowder, composed, for instance, of steatite and silicon carbide, with ametal powder, preferably iron powder, The mixture is composed in such away that the top face of the piston consists of heat insulating powder 2containing little or no metal powder admixtures while the portion of thepiston near the joint 3 between the top part I and the lower part 4 ofthe piston consists of pure metal powder, 1. e. of metal powder withoutceramic admixtures. The top part I of the piston is connected to thelower part 4 by sintering or welding. However M u r it is also possibleto make the top part and the lower part. of a single piece, wherebythe'joint 3' which in the first mentioned embodiment is not visible onthe finished piston, will be dispensed with entirely. In this case, thelower part of the piston would also consist of sintered metal powder,without ceramic admixtures. The transition zone between the homogeneousend parts consisting solely of ceramic powder or'solely'of metal powder,respectively, without'admixtures'of the other component, may then extendover a larger zone, but the piston rings 6 should already be disposed ina part of the piston body which is substantially screened from the heatproduced by .the combustion above the piston, by the insulating layerconsisting of thermally insulating powder 2 While the invention has beendescribed in detail with respect to a now preferred example andembodiment of the invention it will be understood by those skilled inthe art after understanding the invention, that various changes andmodifications may be made without departing from the spirit and scope ofthe invention and it is intended, therefore, to cover all such changesand modifications in the appended claims.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A piston element for an internal combustion engine piston, comprisinga layer of sintered ceramic powder forming a top working surface of theelement, an intermediate zone consisting of a sintered mixture ofceramic and metal powder, with the percentage of metal powder graduallyincreasing towards the bottom of the element, and a bottom partconsisting of sintered metal powder substantially free of ceramicadmixtures for attachment to said piston.

2. A composite piston for internal combustion engines having a topworking surface and comprising sintered metal powder and ceramicmaterial admixed in varying proportions in said piston, said ceramicmaterial forming substantially all of said top surface providing a heatresistant, thermal shock resistant, heat insulat ing layer on saidpiston, and the proportion of metal powder in said admixture graduallyincreasing in said piston below said top surface.

3. A composite piston for internal combustion engines having a topworking surface and comprising sintered metal powder and ceramicmaterial admixed in varying proportions in said piston, said ceramicmaterial forming substantially all of said top surface providing a heatresistant, thermal shock resistant, heat insulating layer on saidpiston, and the proportion of metal powder in said admixture graduallyincreasing up to 100% in portions of said piston more remote from saidtop surface.

4. A composite piston for internal combustion engines having a topworking surface and comprising a sintered admixture of metal powder andceramic material, said top surface being formed substantially entirelyof said ceramic material and being substantially free of said metalpowder providing a heat resistant, thermal shock resistant, heatinsulating layer across the top of said piston and portions of saidpiston below said top surface being formed of continuously decreasingproportions of said ceramic material and continuously increasingproportions of said metal powder.

face of said layer being formed substantially entirely of said ceramicmaterial and the lower surface of said layer being formed substantiallyentirely of said sintered metal powder providing a fusible joining ofsaid layer with said lower metal portion.

'7. A heat insulating, heat resistant, thermal shock resistant top layerfor attachment over the top working surface of a piston for an internalcombustion engine comprising a sintered admixture of metal powder andceramic material, the proportions of said metal powder and said ceramicmaterial continuously varying throughout 5. A composite piston forinternal combustion engines comprising at the top thereof a heatinsulating, heat resistant, thermal shock resistant layer of sinteredceramic material and a solid metal portion below said ceramic layer,said ceramic material being admixed with and gradually blending intosaid solid metal portion at the interface thereof.

6. A composite piston for internal combustion engines comprising a'lowermetal portion and a heat insulating, heat resistant, thermal shockresistant layer over the top of said lower portion, said layercomprising a sintered admixture of metal powder and ceramic material,the top sursaid layer with the top surface of said layer being formedsubstantially of said ceramic material and the bottom surface of saidlayer being formed substantially of metal providing a fusible metalliclower surface on said layer for attachment to said piston.

DIETRICH VON LASSBERG.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,462,655 Philip July 24, 1923 2,202,838 Dake June 4, 19402,362,353 Cate Nov. 7, 1944 e FOREIGN PATENTS Number Country Date495,824 Great Britain Nov. 14, 1938

